Disc brake pad retaining pin

I've lost the pin that screws through calliper and pads on my Formula K18s, probably as a result of losing the C-retainer at some point. The replacements are ridiculously dear - any know of a cheap alternative please, either a supplier that knocks up these parts, or an alternative screw system that will do the same job? Thanks

My current stop gap solution for an old LX caliper is a spare spoke popped through the hole, bent over and clipped off, this stop gap has been in place well over a year and several sets of pads... I don't think I'm going to go looking for a "Proper" pin to replace it really..